Anatomy II Exam II The Respiratory System Functions and Structures of the Respiratory System The Function o Gas exchanges between the blood and external environment occurs in the alveoli of the lungs We need oxygen for electron transport to change generate ATP Digestive glucose generate ATP tied to respiratory system o Passageways to the lungs purify humidify and warm the incoming air o Maintain blood plasma pH Structures o Nose o Pharynx o Larynx o Trachea o Bronchi o Lungs Alveolar ducts Alveolar sacs Alveoli Anatomy of the Respiratory System Upper airways air passages of the head and neck Respiratory tract from larynx throughout the lungs o Composed of the conducting zone conducts are from larynx through lungs respiratory zone site of gas exchange Respiratory bronchioles alveolar ducts alveolar sacs alveoli Functions of the Conducting Zone air passageway 150 mL volume dead space volume increase air temperature to body temperature humidify air o as to be moist for gas exchange to occur removes some particles o dust coughing contains o goblet cells secret mucus o ciliate cells cilia move particles toward mouth to be expelled Anatomy of the Nasal Cavity olfactory receptors are located in the mucosa on the superior surface smell o essential for survival teaches you avoidance o 90 disgusting smells the rest of the cavity is lined with respiratory mucous that o moistens air o trap incoming foreign particles lateral walls have projections called concha shell o increase surface area o increase air turbulence within the nasal cavity the nasal cavity is separated from the oral cavity by the palate o anterior hard palate bone o posterior soft palate muscle storing Paranasal Sinuses cavities within bones surrounding the nasal cavity are called sinuses o gives structural integrity function o lighten the skull o act as resonance chambers for speech o produce mucus that drains into the nasal cavity sinuses are located in the following bones o frontal bone o sphenoid bone o ethmoid bone o maxillary bone Pharynx Throat muscular passage from nasal cavity to larynx three regions of the pharynx o nasopharynx superior region behind nasal cavity o oropharynx middle region behind mouth o laryngopharynx inferior region attached to larynx the oropharynx and laryngopharynx are common passageways for air and food o cant breath while eating choking because of branching design flaw lead to death routes air and food into proper channels plays a role in speech made of eight rigid hyaline cartilages and a spoon shaped flap of elastic cartilage Larynx Voice Box epiglottis Structures of the Larynx thyroid cartilage o largest of the hyaline cartilages o protrudes anteriorly Adam s apple epiglottis o protects the superior opening of the larynx o routes food into the esophagus and air toward the trachea o when swallowing the epiglottis forms an lid over the opening of the larynx vocal folds true vocal cords vibrate with expelled air to create sound speech glottis opening between vocal cords Trachea Windpipe four inch long tube that connects larynx with bronchi walls are reinforced with C shaped hyaline cartilage lined with ciliated mucosa o beat continuously in the opposite direction of incoming air o expel mucus loaded with dust and other debris away from the lungs Structures of the Thoracic Cavity chest wall is air tight protects lungs o rib cage sternum o thoracic vertebrae o muscles internal external intercostals diaphragm pleura is a membrane lining of lungs and chest wall o pleural sac around each lung o intrapleural space filled with intrapleural fluid volume 15 mL helps reduce friction Lungs occupy most of the thoracic cavity o heart occupies central portion called Mediastinum apex is near the clavicle superior portion base rests on the diaphragm inferior portion each lung is divided into lobes by fissures o left lung two lobes o right lung three lobes Coverings of the Lungs serosa covers the outer surface of the lungs o pulmonary visceral pleura covers the lung surface o parietal pleura lines the walls of the thoracic cavity pleura fluid fills the area between layers of pleura to allow gliding these two pleural layers resist being pulled apart Bronchial Respiratory Tree Divisions All but the smallest of these passageways have reinforcing cartilage in their walls o Primary bronchi o Secondary bronchi o Tertiary bronchi o Bronchioles Respiratory Zone Structures o Terminal bronchioles o Respiratory bronchioles o Alveolar ducts o Alveolar sacs Bunch of breaks o Alveoli air sac Individual break Primary site of gas exchange is only at the alveoli Alveoli Alveoli site of gas exchange 300 million alveoli lung Rich blood supply capillaries for sheet over alveoli Type I alveolar cells o Make up wall of alveoli o Single layer epithelial cells Type II alveolar cells secrete surfactant Alveolar macrophages Respiratory Membrane Air Blood Barrier Thin squamous epithelial layer lines alveolar walls Alveolar pores connect neighboring air sacs Pulmonary capillaries cover external surfaces of alveoli One side of the membrane is air and on the other side is blood flowing past Barrier for diffusion o Type I cells and basement membrane o Capillary endothelial cells and basement membrane o 0 2 microns thick thin Surfactant Reduces the surface tension of a liquid Factors Affecting Pulmonary ventilation Compliance ease with which lungs can be stretched Lung compliance elasticity of the lung Normal value 0 1 L cm H20 Too elastic because of scar tissue decrease compliance hard to stretch lung tuberculosis hard to inspire easy to expire Not elastic enough because of tissue breaking down increase compliance and less recoil emphysema easy to inspire hard to expire Surface tension of lungs greater tension less compliant Respiratory volumes and Capacities Normal breathing moves about 500mL of air with each breath this respiratory volume is tidal volume TV Many factors that affect respiratory capacity o A person s size sex age physical condition Inspiratory reserve volume IRV o Amount of air that can be taken in forcibly over the tidal volume Usually between 2100 and 3200 mL Expiratory reserve volume ERV o Amount of air that can be forcibly exhaled o Approximately 1200 mL Residual volume o Air remaining in lung after expiration o About 1200 mL Vital capacity o The total amount of exchangeable air o Vital capacity TV IRV ERV o Dead space volume not the same as residual volume Air that remains in conducting zone and never reaches
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